Pollution Control - rebuild or remove?

[Merl]

The pollution control stuff on my D21 is in worse-than-not-having condition and I'm trying to figure how much I need to keep and what to simply eliminate.

This 1986.5 D21 has a canister up near the driver's front wheel well that looks like it had a hose coming up from the exhaust and into a metal canister that held some kind of air filter. On the bottom of that canister looks like a drain for water that goes down through the fender in front of the tire, and on the other side of the filter is a large hose that goes to some sort of control module behind the headlight, and from there over to the exhaust manifold. Also off of that control module is a couple of vacuum lines that snake over to the TB and air cleaner housing. There are other hoses going to a small canister with electrical lines coming off of it.

The issue is that the metal air filter housing has literally rusted away, filter included, and the hoses are simply open to the air. There is fuel rich exhaust coming up through this hose into the engine bay (I intend to replace the fuel injector in hopes of fixing the fuel-rich problem), and it's noisy and smoky. Even if this truck is pollution control exempt I doubt this would pass state inspection because of the obvious exhaust-up-front issue.

So does anyone know what that metal canister and the control/vacuum/control block are for and if it would hurt just to remove them and block the hoses? I can't believe removing this stuff would make the truck run any *worse*, and I'd certainly rather remove this stuff than rebuild it.

[LugNut1990]

Here are some things in TX to read first:


https://texreg.sos.state.tx.us/public/readtac$ext.TacPage?sl=R&app=9&p_dir=&p_rloc=&p_tl oc=&p_ploc=&pg=1&p_tac=&ti=30&pt=1&ch=114&rl=20


https://www.tceq.texas.gov/airqualit...tampering.html

[cadillacdude1975]

I blocked/removed all that stuff when I swapped engines. New driver side exhaust manifold that has the plug, welded the converter line shut and deleted the egr. Runs like a champ. Oh it has a carb.

[SBJ]

That's the air induction valve. Functionally it does the same thing as a smog pump on older domestic vehicles, which is to add air into the exhaust stream to get the catalytic converter up to temperature faster. The truck will run just fine without it.

[jp2code]

Where are you in Texas? Some spots have stricter requirements than others.

I'm in Longview. They do not have a smog check here, but they do have to physically see a catalytic converter connected to the exhaust when they look under the vehicle. The neighboring towns don't require that, but I cannot get my tags in those towns since I do not live there.

[Jason Bourne]

It is my understanding that vehicles 25 yrs and older are exempt from smog tests in Texas. When I took my son’s truck (1993) to get registered last year they performed a safety check only, for a cost of $7. The safety check is for things like turn signals, brake lights, horn, etc.. The kid at the station didn’t even drive it for the brake check because he didn’t know how to drive stick. I live in Williamson county which does require emissions testing on my other vehicles.

[Merl]

I tried to read up on the Texas regs for this, but they're a bit confusing. I found references to "thou shalt not remove emissions equipment" as noted in one of the response links, but I also found reference to stuff from TxDOT stating nothing older than 1995 requires an emissions test any longer. Which makes me think that as long as it's still on the vehicle it doesn't actually have to work... which seems kinda self-defeating.

I'm in Rockwall county, which is one of *those* counties, but I'm actually planning on passing this thing on to my father who lives in Kerr county which does not have the higher standard. The exhaust system is actually in good shape, catalytic converter and muffler included, and I don't plan on taking any of that stuff off.

I'm just trying to figure how I even *could* replace this emissions stuff since you can't get it any more... like the metal canister fed by the exhaust which feeds the air induction valve which feeds who-knows-what. It is literally rusted into nothing. I guess if I am flagged I'd have to try and make my own out of a coffee can or something. Seems a little eye-rolling.

[Merl]

Originally Posted by Jason Bourne

It is my understanding that vehicles 25 yrs and older are exempt from smog tests in Texas. When I took my son’s truck (1993) to get registered last year they performed a safety check only, for a cost of $7. The safety check is for things like turn signals, brake lights, horn, etc.. The kid at the station didn’t even drive it for the brake check because he didn’t know how to drive stick. I live in Williamson county which does require emissions testing on my other vehicles.

At the risk of getting too location specific for the discussion board...
Right, I think Rockwall is designated the same as Williamson. I'm curious, did they look under the hood at all? Any kind of visual check for it to even be there? I guess it may depend on the inspector, but I would think that a visual inspection would be part of the procedure.

[Jason Bourne]

Originally Posted by Merl

At the risk of getting too location specific for the discussion board...
Right, I think Rockwall is designated the same as Williamson. I'm curious, did they look under the hood at all? Any kind of visual check for it to even be there? I guess it may depend on the inspector, but I would think that a visual inspection would be part of the procedure.

I’m pretty sure the hood was never raised, but it has been a year so my memory is not exactly fresh. My sons truck does have the charcoal canister, egr valve, and everything else still installed. Whether or not it functions is a mystery.

My son was actually planning to take the truck to get inspected soon since it is due. I will try and post an update as to whether or not the hood gets raised.

[XoXSciFiGuy]

All the Texas smog rules are here: They even name the counties where it is required. Anything 25 years old or older is exempt, but they still do a safety inspection.

https://texascarlaws.com/smog-laws/